What is WGS84, and where is it used?

• A. WGS84 is a regional datum used only in North America.
• B. WGS84 is a star catalog used for celestial navigation.
• C. WGS84 is a local ellipsoid variant used for mapping coastal zones.
• D. WGS84 is a global geodetic datum used by GPS and other GNSS, providing a consistent global reference frame.

Answer: (D)

WGS84 is a global geodetic datum and reference frame that defines a single, worldwide ellipsoid and a fixed Earth-centered, Earth-fixed (ECEF) coordinate system. It provides latitude, longitude, and height in a consistent global framework, so measurements from GPS and other GNSS can be compared and combined anywhere on the globe. This global scope distinguishes it from regional datums that are tuned for specific areas. GPS satellites broadcast positions in this frame, and receivers report coordinates in WGS84, enabling reliable navigation, mapping, and surveying worldwide.